Method and apparatus for treating liquids to inhibit growth of living organisms

ABSTRACT

A method and apparatus for treating a liquid to inhibit growth of living organisms therein by adding to the liquid an active biocidal ingredient formed by mixing an oxidant and an amine source, by: producing a predetermined dilution of the oxidant; producing a predetermined dilution of the amine source; synchronously metering the two dilutions into a conduit to continuously mix therein according to a predetermined ratio to produce the active biocidal ingredient having high reproducibility, stability and efficacy in situ in the conduit; and continuously injecting the active biocidal ingredient, as it is produced in situ in the conduit, directly from the conduit into the liquid being treated.

This application is a 371 of PCT/U.S. Ser. No. 95/12322 file Sep. 26,1995.

The present invention relates to a method of treating a liquid toinhibit the growth of living organisms. The invention is particularlyuseful to prevent biological fouling of circulating water, and istherefore described below with respect to that application, but it willbe appreciated that the invention could be used in other applications aswell.

As described in published European Patent Application No. 92109015.5,published Sep. 12, 1992 (corresponding to Israel Patent Application98352 filed Aug. 3, 1991), biological fouling of circulating water is awell known problem caused by algae, fungi, bacteria, and other simplelife forms found in circulating water. That patent publication describescontrolling biofouling in high chlorine demand waters by mixing twocomponents, one of which is an oxidant and the other an ammonium salt,and adding the mixture substantially immediately to the aqueous systemto be treated. This produces the active biocidal ingredient, asdescribed therein. A large number of examples of oxidants and ammoniumsalts are described in that patent publication, and the contents of thatpatent publication are therefore incorporated herein by reference.

A problem encountered in this method of treating liquid to inhibitgrowth of living organisms, however, is that the concentrated activebiocidal ingredient is extremely non-stable chemically and quicklydecomposes upon formation with the result that there is a fast drop inpH. This is especially so for the active biocidal ingredients derivedfrom ammonium bromide where the decomposition results in the undesirableformation of HOBr. Therefore, when conventional dosing pumps and mixersare used, the formed active biocidal ingredient quickly decomposes andloses its efficacy. Also, while the pH range of such concentrated activebiocide is theoretically 8.0-12.5, actually the pH never exceeds 8.0because of the fast decomposition. In addition, the ammonium salts mustbe supplied in excess in order to decrease the decomposition rate.

An object of the present invention is to provide a method and apparatusof the foregoing type but having advantages in the above respects.

According to one aspect of the present invention, there is provided amethod of treating a liquid to inhibit growth of living organismstherein by adding to the liquid an active biocidal ingredient formed bymixing an oxidant and an amine source, comprising producing apredetermined dilution of the oxidant; producing a predetermineddilution of the amine source; synchronously metering the two dilutionsinto a conduit to continuously mix therein according to a predeterminedratio to produce said active biocidal ingredient having highreproducibility, stability and efficacy in situ in the conduit; andcontinuously injecting the active biocidal ingredient, as it is producedin situ in the conduit, directly from the conduit into the liquid beingtreated.

By "synchronously metering" the two dilutions, it is meant metering theamine source and the oxidant to the two water streams in a manner havingthe same time and molar relation and then metering the two dilutions ina manner also having the same time and molar relation. In furtherexamples described below, the synchronous metering is effected byventuri pumps but could also be effected in other manners, such as byperistaltic pumps and pulsatile pumps operating with the same time anddisplacement relationship.

According to another aspect of the invention, there is provided a methodof treating a liquid to inhibit growth of living organisms therein byadding to the liquid an active biocidal ingredient formed by mixing anoxidant and an amine source, characterized in continuously andsynchronously injecting a quantity of the oxidant into a first stream ofwater passing through a first conduit to produce therein a predetermineddilution of the oxidant; continuously and synchronously injecting aquantity of the amine source into a second stream of water passingthrough a second conduit to produce therein a predetermined dilution ofthe amine source; continuously and synchronously injecting the first andsecond streams into a third conduit according to a predetermined ratioto produce the active biocidal ingredient in situ in the third conduit;and continuously injecting the active biocidal ingredient, as it isproduced in situ in the third conduit, from the third conduit into theliquid being treated.

According to further features in the described preferred embodiments,the oxidant is continuously injected into the first stream of water by afirst dosing pump conducting the first stream of water through the firstconduit and connected to a reservoir of the oxidant. The amine source isalso continuously injected into the second stream of water by a seconddosing pump, synchronously operated with the first dosing pump,conducting the second stream of water through the second conduit andconnected to a reservoir of the amine source. Both dosing pumps arepreferably venturi tubes, peristaltic pumps, high-frequency,low-displacement pulsatile pumps, or the like.

As will be described more particularly below, using two synchronouslyoperated dosing pumps to produce a predetermined dilution of the tworeactants before mixing them together, and immediately mixing themtogether to produce the active biocidal ingredient in situ just as it isbeing added to the liquid being treated, were surprisingly found togreatly increase the reproducibility, stability and efficacy of theactive ingredient (demonstrated by the stable pH of the concentratedactive biocidal ingredient), as compared to the prior art methods wherethe two reactants are merely mixed together and added to the liquidbeing treated as described in the above cited European PatentApplication No. 92109015.5.

Preferably, the concentrated active biocidal ingredient, as produced insitu, should have a pH of at least 7.0, more preferably over 9.0, beforebeing injected into the liquid being treated. The liquid being treatedshould preferably have a pH of 5-10.5, more preferably 7-9. The activebiocidal ingredient produced in situ is injected into the liquid beingtreated preferably to a concentration of 0.5-300 ppm, more preferably3-10 ppm, expressed as chlorine.

The amine source may be selected from an oxidizable nitrogen derivative,preferably from the group of ammonium salts, organic amines, sulfamicacid, hydrazine, dimethylhydantoin, and cyanuric acid benzotriazole,hexamethylene diamine, ethylenediamine, ethanolamine, or mixturesthereof. The amine source may contain a detergent, surfactant, watertreatment chemicals, color, and/or a base, e.g. NaOH or NH₃ OH.Preferably, it has a concentration of 0.1-50%, more preferably 2.5-30%,and could be equimolar to Cl₂. The diluted amine source preferably has aconcentration of 0.1-6.0% and is equimolar to Cl₂.

The oxidant is preferably selected from the group of sodium hypochloriteand calcium hypochlorite. It may, however, be a solution of chlorine, inwhich case the amine source should be a solution containing an excessbase corresponding to at least 10% NaOH. Preferably, the oxidant has aconcentration of 0.3-15%, more preferably 5-15%, expressed as Cl₂.

The diluted oxidant preferably has a concentration of 0.1%-2.0%,expressed as Cl₂.

The invention also provides apparatus for treating a liquid to inhibitgrowth of living organisms therein according to the above-describedmethod.

The novel method and apparatus enable the constant ratio ofoxidant/amine source to be maintained, thereby avoiding the need to useexcess amine source in order to stabilize the reaction product and tomaintain a reproducible product containing almost no degradationproducts. In addition, the novel method produces an efficient in situdilution of both the oxidant and the amine source, thereby avoiding theneed for pre-dilution of the respective ingredients in water, storing inlarge tanks, etc.

The above-described efficient method for producing an active biocidalingredient allows a comparison to be made between efficacies exhibitedby active biocidal ingredients derived from various amine sources andammonium salts. Such a comparison shows that an active biocidalingredient derived from ammonium bromide exhibits superior efficacy andfaster rate of kill in basic media as compared to active biocidalingredients derived from other amine sources; and that for treatingacidic media, the active biocidal ingredient derived from ammoniumcarbonate exhibits superior efficacy.

Further features and advantages of the invention will be apparent fromthe description below.

The invention is more particularly described with respect to a number ofexamples set forth below, and also with respect to the accompanyingdrawing wherein:

FIG. 1 is a block diagram illustrating one form of apparatus constructedin accordance with the present invention; and

FIG. 2 is a similar block diagram illustrating another apparatus inaccordance with the present invention.

The apparatus illustrated in FIG. 1 is intended to treat a liquid, suchas water in a cooling tower, waste water, or the like, used at alocation, schematically indicated at 2 in the drawing, to disinfect thatliquid or otherwise to inhibit growth of living organisms in thatliquid. This is done by adding to the liquid at location 2 an activebiocidal ingredient formed by mixing in situ two solutions, namely anoxidant solution within a reservoir 4, and an amine source solutionwithin a reservoir 6.

As shown in the drawing, water, e.g., tap water is fed from a source 8via a water pipe 10 through a pair of branch lines 12, 14, connected inparallel to each other, to a common outlet pipe 16 leading to the liquidto be treated at the location 2. Each of the two parallel branch lines12, 14, includes a venturi tube 18, 20 having an inlet port 18a, 20a,connected in the respective branch line 12, 14, and an outlet port 18b,20b, connected to the common outlet line 16 leading to the liquid to bedisinfected. Each of the venturi tubes 18, 20, includes a third port18c, 20c, leading to the reservoir 4, 6, of the respective solution tobe added to the water flowing through the outlet line 16.

The two venturi tubes 18, 20, thus constitute dosing pumps whichcontinuously and synchronously inject both oxidant solution fromreservoir 4, and the amine source solution from reservoir 6, into thewater from source 8 in the required predetermined proportions. These twochemicals continuously and instantaneously react with each other in theoutlet pipe 16 so that the reaction product, namely the active biocidalingredient produced by the reaction of these two chemicals, isimmediately and continuously produced in situ as it is introduced intothe liquid at the location 2 to be treated.

The two branch lines 12, 14 for the two venturi tubes 18, 20 includecontrol valves 22, 24, which enable the flow rate of the water to becontrolled via the two venturi tubes 18, 20. Lines 26, 28 connecting thetwo reservoirs 4,6 to their respective venturi tubes 18, 20 also includevalves, shown at 30, 32, for controlling the dosage of the chemicalsinto the water passing through the venturi tubes. The latter valves alsoenable the supply of chemicals to be terminated at the end of theintroduction of the active biocidal ingredient, so that continued flowof the water via the branch lines 12, 14 and the outlet line 16 willwash away any residue of these chemicals, or their decompositionproducts, and thereby avoid accumulation of decomposition products whichform at the end of each disinfection cycle in the outlet line 16.

The control of the foregoing valves is done by a control system,schematically illustrated by block 40. One of the inputs to controlsystem 40 is a light sensor 42 which senses the light from a source 44passing through a transparent window 46 in the outlet line 16. Thus, anoptical property of the water passing through outlet line 16 can be usedfor continuously monitoring the relative dosage of the two chemicalsfrom sources 4, 6, introduced into the water passing through the twoventuri tubes 18, 20, and thereby into the liquid to be disinfected.

Where the amine source includes ammonium bromide, an orange colorappears if the active biocidal ingredient decomposes. Light sensor 42,therefore, would include a filter making it particularly sensitive tothe orange color.

The pH of the concentrated active ingredient decreases as theconcentrated active biocidal ingredient decomposes. Outlet line 16,therefore, may also include a pH sensor 47 for sensing the pH of theconcentrated active biocidal ingredient, and controlling the controlsystem 40 in response thereto.

Control system 40 also controls the supply of the water from source 8via an electrical valve 48. Control system 40 can further control analarm 50 or other signalling device. The illustrated system may furtherinclude a timer 52 which is presettable to fix both the times, and thetime intervals, during which the active biocidal ingredient is to beapplied via the outlet line 16 to the liquid to be disinfected.

The water supply line 10 from the water source 8 to the two branch lines12, 14, could include additional control devices. For purposes ofillustration, the accompanying drawing schematically illustrates thefollowing additional control devices: a manual control valve 53,enabling manual control of the water flow from the source 8; a pressurereducer 54 for reducing the pressure from the source; a pressure sensor56 which may also be used as an input into the control system 40; a flowmeter 58 for indicating the flow rate or flow volume; a pressure gauge60 for indicating the pressure in line 10; a pressure relief valve 62;and a one-way valve 64.

Preferably, the two venturi tubes 18, 20, and their controls, aredesigned so as to synchronously feed the same volumes of solutions fromthe two sources 4, 6 even though the viscosities of the two solutionsmay be different. The illustrated system operates at a constantpredetermined water pressure and at a constant ratio of predetermineddilution of the two solutions to the water passing via the branch lines12, 14, through the two venturi tubes 18, 20. Each of these parameterscan be controlled as described above so that the solutions from the twosources 4, 6, are simultaneously and synchronously injected in thedesired predetermined proportions with respect to each other, and alsowith respect to the water flowing through the venturi tubes 18, 20 fromthe source 8.

As indicated earlier, the solution in reservoir 4 is an oxidant, and thesolution within reservoir 6 is an amine source. Preferably, the latteris an ammonium salt containing a halide, sulfate, nitrate, carbonate,bromide, or mixtures of any of the ammonium salts, surfactants,detergents, etc., mentioned above. The oxidant is preferably sodiumhypochlorite. The above-cited published patent application discloses alarge number of examples which are generally useful also in the presentinvention. Below are described additional examples particularly usefulwith the apparatus illustrated in the drawing.

The concentrated active biocidal ingredient injected into the liquidshould have a pH greater than 7.0, preferably greater than 9.0, andshould be injected at a rate to maintain in the concentrated activebiocidal ingredient a stable pH of at least 7.0. The active biocidalingredient is normally very non-stable, and upon decomposition there isa sharp decrease in the pH. Accordingly, efficient production of theactive biocidal ingredient maintains a stable pH of at least 7.0,preferably greater than 9.0. It delays the decomposition of thisotherwise extremely non-stable product at least for 5 minutes andthereby prolongs its efficacy. Stability is maintained under thesespecial dosing conditions even in the presence of a 15% excess ofoxidant. (Mole ratio of amine source to chlorine of 1:1.15.)

As indicated earlier, the dosing pumps 18, 20, could be other forms ofpumps. This is shown in FIG. 2, wherein the venturi pumps 18, 20 arereplaced by dosing pumps P₁, P₂, which may be peristaltic pumps,pulsatile pumps, and the like. The two pumps P₁, P₂ are also controlledby the control system 40 so as to synchronously meter the liquids fromthe two reservoirs 4, 6, via feed lines 26, 28, in the same manner asthe venturi pumps 18, 20, in the system described above with respect toFIG. 1. All the other elements of the system in FIG. 2 are the same asin FIG. 1 and operate in the same manner.

Following are more specific examples of the above-described method andthe chemicals used for treating water to inhibit the growth of livingorganisms. These examples have been found particularly effective forinhibiting the growth of Legionella Pneumophila in cooling water. Theyalso show that active biocidal ingredients derived from different aminesources exhibit different efficacies; and that an active biocidalingredient derived from ammonium bromide exhibits superior efficacy,resulting in faster rate of kill as compared to those derived from otheramine sources whenever the pH of the treated media is basic, while theactive biocidal ingredient derived from ammonium carbonate exhibitssuperior efficacy in acidic media.

The concentrated solutions of the active biocidal ingredient of thefollowing Examples 1-11 were prepared by using apparatus providing acontinuous, synchronous production of the active biocidal ingredient inaccordance with the above-described method. Examples 12-18 compare the"batch formations" in the method of the above-cited European PatentApplication No. 92109015.5 with the continuous formations described inthe present application. The "batch dilution factor" refers to the finaldilution of both NaOCl and the ammonium source in the concentratedbiocidal solution.

The decomposition rate of the concentrated active ingredient wasmonitored in the examples below by measuring the residue of combinedchlorine in the concentrate.

EXAMPLE 1

A concentrated solution of the active biocidal ingredient was preparedfrom ammonium chloride (82.9 gr/L) and sodium hypochlorite (10%expressed as Cl₂). The rate of decomposition of the concentrated activeingredient was monitored with time as follows:

                  TABLE 1                                                         ______________________________________                                        Time               Residual Oxidant                                                                            NH.sub.4  +                                    (Minute) pH expressed as ppm Cl.sub.2 ppm                                   ______________________________________                                         0       10.49     9200          2400                                           12 10.39 9600 2500                                                            30 10.34 9500 2500                                                            60 10.27 9200 2500                                                            120  10.16 9000 2500                                                        ______________________________________                                    

EXAMPLE 2

A concentrated solution of the active biocidal ingredient was preparedfrom ammonium bromide (152 gr/L) and sodium hypochlorite (10% expressedas Cl₂). The rate of decomposition of the concentrated active biocidalingredient was monitored with time as follows:

                  TABLE 2                                                         ______________________________________                                        Time               Residual Oxidant                                                                            NH.sub.4  +                                    (Minute) pH expressed as ppm Cl.sub.2 ppm                                   ______________________________________                                         0       10.55     7300          1900                                           11 10.08 6800 1900                                                            22  9.56 6700 1800                                                            43  2.02 1000 1100                                                          ______________________________________                                    

Ammonium bromide decomposes much faster than other active ingredientsderived from other ammonium salts.

EXAMPLE 3

A concentrated solution of the active biocidal ingredient was preparedfrom ammonium sulfate (102.5 gr/L) and sodium hypochlorite. The rate ofdecomposition of the concentrated active biocidal ingredient wasmonitored with time:

                  TABLE 3                                                         ______________________________________                                        Time               Residual Oxidant                                             (Minute) pH expressed as ppm Cl                                                                              .sub.2 NH.sub.4  +                           ______________________________________                                         0       11.0       9000         2300                                           14 10.98 10000 2400                                                           38 10.88  8400 2400                                                           150  10.48 -- --                                                            ______________________________________                                    

EXAMPLE 4

A concentrated solution of the active biocidal ingredient was preparedfrom ammonium hydrogen phosphate (102.4 gr/L) and sodium hypochlorite.The rate of decomposition of the concentrated active biocidal ingredientwas monitored with time as follows:

                  TABLE 4                                                         ______________________________________                                        Time               Residual Oxidant                                             (Minute) pH expressed as ppm Cl                                                                              .sub.2 NH.sub.4  +                           ______________________________________                                         0       9.70      8000          2000                                            8 9.64 8300 2100                                                             26 9.56 8100 2100                                                             80 9.39 -- --                                                               ______________________________________                                    

EXAMPLE 5

A concentrated solution of the active biocidal ingredient was preparedfrom ammonium carbonate (74.4 gr/L) and sodium hypochlorite. The rate ofdecomposition of the concentrated active biocidal ingredient wasmonitored with time as follows:

                  TABLE 5                                                         ______________________________________                                        Time               Residual Oxidant                                             (Minute) pH expressed as ppm Cl                                                                              .sub.2 NH.sub.4  +                           ______________________________________                                         0       10.1      8000          2100                                           17 10.04 8000 2100                                                             16h  9.32 7500 1800                                                           24h  9.00 7000 1600                                                        ______________________________________                                    

EXAMPLE 6

The efficacy of active biocidal ingredients derived from variousammonium salts against Bacillus in phosphate buffer, pH of the media 7.0(initial count: 4×10⁶ cfu/ml) was tested as follows:

                  TABLE 6                                                         ______________________________________                                                Dosage                                                                   ppm                                                                          Ammonium expressed Viable Count cfu/ml after                                Salt    as Cl.sub.2                                                                            1 min.  1 hr. 3 hr. 5 hr. 23 hr.                             ______________________________________                                        (NH.sub.4).sub.2 CO.sub.3                                                             1.2      9 × 10.sup.5                                                                    3 × 10.sup.5                                                                  6 × 10.sup.4                                                                  2 × 10.sup.4                                                                  2 × 10.sup.2                   (NH.sub.4).sub.2 HPO.sub.4 1.3 8 × 10.sup.5 4 × 10.sup.5 7                                                 × 10.sup.4 8 ×                                                    10.sup.3 0                           NH.sub.4 Cl 8 × 10.sup.5 1.3 3 × 10.sup.5 3 ×                                                        10.sup.4 2 × 10.sup.3 0                                                  NH.sub.4 Br 1.3 1 ×                                                    10.sup.6 8 × 10.sup.4 2                                                 × 10.sup.3 7 ×                                                    10.sup.2 0                         ______________________________________                                    

EXAMPLE 7

The efficacy of active biocidal ingredients derived from variousammonium salts against Bacillus in carbonate buffer, pH of the media10.0 (initial viable count: 4×10⁶ cfu/ml) was tested as follows:

                  TABLE 7                                                         ______________________________________                                                Dosage                                                                   ppm                                                                          Ammonium expressed Viable Count cfu/ml after                                Salt    as Cl.sub.2                                                                            1 min.  1 hr. 3 hr. 5 hr. 23 hr.                             ______________________________________                                        (NH.sub.4).sub.2 HPO.sub.4                                                            2.25     9 × 10.sup.5                                                                    6 × 10.sup.5                                                                  3 × 10.sup.5                                                                  4 × 10.sup.5                                                                  2 × 10.sup.4                   NH.sub.4 Cl 2.25 9 × 10.sup.5 4 × 10.sup.5 2 ×                                                       10.sup.5 2 × 10.sup.5 1                                                 × 10.sup.4                     NH.sub.4 Br 2.25 1 × 10.sup.6 6 × 10.sup.5 2 ×                                                       10.sup.5 2 × 10.sup.5 2                                                 · 10.sup.3                ______________________________________                                    

EXAMPLE 8

Control of mixed cultures of microorganisms in a 2% sizing ketosuspension. The pH of the media was 5.5.

                  TABLE 8                                                         ______________________________________                                                             Viable Count                                                            Dosage Expressed                                                                          cfu/ml                                               Ammonium Salt as ppm Cl.sub.2 after 6 hours                                 ______________________________________                                        (NH.sub.4).sub.2 CO.sub.3                                                                    9.5         3 × 10.sup.2                                   NH.sub.4 Br 9.5 7 × 10.sup.3                                          ______________________________________                                    

EXAMPLE 9

Control of Legionella Pneumophila in a cooling tower:

The cooling tower was operated with soft water (see water analysisbelow). The system was treated with phosphonate-polyacrylate as acorrosion inhibitor. Microbial analysis of the cooling water: totalaerobic count:2×10⁵ cfu/ml; total anaerobic count: 9×10³ cfu/mlLegionella Pneumophila: 9×10³ cfu/ml. The deck and basin of the coolingtower were covered with algae.

The cooling tower was shock dosed with the active biocidal ingredientformed with ammonium sulfate and sodium hypochlorite. The quantity 90ppm (expressed as Cl₂) of the active biocidal ingredient were added tothe cooling water during 30 minutes, and was left in the water for anadditional hour.

The microbial population of the cooling tower, monitored 49 hours afterthe shock treatment, revealed a total aerobic count of 10 cfu/ml, andLegionella Pneumophila was not detected in the water following shocktreatment.

                  TABLE 9                                                         ______________________________________                                        Cooling Water Analysis:                                                                       Conductivity:                                                                            4080 μs                                            Ca: 87.0 ppm as CaCO.sub.3                                                    Cl: 830 ppm as Cl                                                             Si: 19 ppm                                                                    P: 1.7 ppm as PO.sub.4                                                        pH: 8.8                                                                       Alkalinity: 590 ppm as CaCO.sub.3                                             Fe: 2.5 ppm                                                                ______________________________________                                    

EXAMPLE 10

The efficacy of the active biocidal ingredient derived from variousammonium salts in a cooling water (pH 9.0) was tested as follows:

The water, taken from a cooling tower, contained a mixture ofphosphonate and dispersant as scale and corrosion inhibitors. Wateranalysis: Ca:550 ppm as CaCO₃ ; total phosphate 25.0 ppm as PO₄ ;Si:43.0 ppm; Cl:390 ppm; alkalinity M-alkalinity:455 ppm;P-alkalinity:120 ppm. Conductivity:2580 μs.

                  TABLE 10                                                        ______________________________________                                        Ammonium   Dosage ppm  Viable Count                                                                             cfu/ml after                                  Salt expressed as Cl.sub.2 90 min. 18 h.                                    ______________________________________                                        (NH.sub.4).sub.2 CO.sub.3                                                                6.0         1 × 10.sup.5                                                                       0                                             (NH.sub.4).sub.2 HPO.sub.4 6.0 6 × 10.sup.4 0                           NH.sub.4 Br 6.0 6 × 10.sup.2 0                                          Control -- 1 × 10.sup.5 3 × 10.sup.4                            ______________________________________                                    

EXAMPLE 11

A concentrated solution of the active biocidal ingredient was preparedfrom mixtures of ammonium bromide (152 gr/L)and ammonium sulfate (102.5gr/L) at the listed molar ratio, and sodium hypochlorite. The rate ofdecomposition of the concentrated active biocidal ingredient wasmonitored as follows:

                  TABLE 11                                                        ______________________________________                                        SO.sub.4 /Br      SO.sub.4 /Br    SO.sub.4 /Br                                  3:1  1:1  1:3                                                               Time   pH         Time   pH       Time pH                                     ______________________________________                                         0     10.45       0     10.02     0   10.65                                    12 10.19  12 9.86 12 10.07                                                    32 9.98 30 9.40 30 9.59                                                       48 9.84 48 9.02 48 8.89                                                       58 9.72 58 8.77 59 6.6                                                        62 9.67 62 8.53 61 2.66                                                       126  7.02 71 7.52 71 2.01                                                   ______________________________________                                    

EXAMPLE 12

An active biocidal ingredient derived from sulfamic acid and NaOCl wasprepared as follows: Sulfamic Acid: 13.7%; NaOCl: 7.2% expressed as Cl₂.Batch dilution factor: 1:20; continuous synchronous dilution factor:1:14

By "batch dilution factor" is meant the volume ratio of both the volumeof the chlorine source (≈10% as Cl₂) and of the amine source (equimolarto chlorine) to the volume of water in the concentrated activeingredient. By "continuous synchronous dilution factor" is meant thevolume ratio of both the chlorine source (≈10% as Cl₂) and the aminesource (equimolar to chlorine) to the volume of water in the continuoussynchronous dilution process.

                  TABLE 12                                                        ______________________________________                                        Yield % of concentrated active biocidal ingredient derived from:                   Sulfamic Acid (pH 7.73)                                                                         Sulfamic acid (pH 1.14)                                     batch   continuous                                                                             pH of con-                                                                           batch continuous                                                                           pH of con-                            t =  process process centrate process process centrate                      ______________________________________                                        0    100     100      12.23  100   100    11.50                                 30 m 91.2 100 12.29 -- 100 11.50                                              12 h 77.8 102.1 12.14 -- -- --                                                20 h 72.2 83 11.83 69.4 100 10.32                                           ______________________________________                                    

EXAMPLE 13

An active biocidal ingredient derived from Hydrazine hydrochloride andNaOCl was prepared as follows: Hydrazinium hydrochloride: 14.8% NaOCl:7.2% expressed as Cl₂

                  TABLE 13                                                        ______________________________________                                        Yield % of concentrated active biocidal ingredient derived from:                   Hydrazine HCl     Hydrazine HCl + NaoH                                     pH 0.0 pH 7.60                                                                   batch   continuous                                                                             pH of con-                                                                           batch continuous                                                                           pH of con-                            t = process process centrate process process centrate                       ______________________________________                                        t =  19.44   24.0     0.32   8.33  100    8.20                                  5 m                                                                           t = 0 0 0 0 0 8.17                                                            24 h                                                                        ______________________________________                                    

EXAMPLE 14

An active biocidal ingredient derived from NH₄ Br and Ca(OCl)₂ wasprepared as follows: Ca(OCl)₂ : 0.35% expressed as Cl₂ NH₄ Br: 5%expressed as Cl₂ Concentrated active biocidal ingredient: 0.07 expressedas Cl₂ Continuous process dilution factor: 1:4.8

The following table sets forth the yield (%) of the active biocidalingredient.

                  TABLE 14                                                        ______________________________________                                                 Batch       Continuous                                                                              pH of                                            t = process process concentrate                                             ______________________________________                                        5 min.   10%         60%       9.08                                           ______________________________________                                    

EXAMPLE 15

An active biocidal ingredient derived from ammonium bromide mixed withTween 20 (Polyoxyethylene Sorbitan Monolaurate) and NaOCl was preparedas follows: Amine source: NH₄ Br (14%) mixed in Tween 20 (1.4%). NaOCl:8% expressed as Cl₂ Concentrated active biocidal ingredient: 0.6%expressed as Cl₂. Continuous process: dilution factor 1:13.3; N/Cl₂ 1:1Batch process: dilution factor 1:20; 0.4% expressed as Cl₂ Molar ratioN:Cl₂ =2.1

The following table sets forth the yield (%) of the active biocidalingredient.

                  TABLE 15                                                        ______________________________________                                               Batch     Continuous                                                                              Concentrate                                        t =      process     process   pH                                             ______________________________________                                         5 min   12.5        100       8.90                                             10 min -- 51.6 6.60                                                         ______________________________________                                    

EXAMPLE 16

An active biocidal ingredient derived from ammonium hydroxide and NaOClwas prepared as follows: NH₄ OH: 2.4% NaOCl: 11.5% expressed as Cl₂Continuous process: dilution factor: 1:10. Molar ratio N/Cl₂ : 1.3:1.0.Concentrated active biocidal ingredient: 1.15% expressed as Cl₂ Batchprocess: dilution factor: 1:20; molar ratio N/Cl₂ =2:1.

The following table sets forth the yield (%) of the active biocidalingredient.

                  TABLE 16                                                        ______________________________________                                                 Batch       Continuous                                                                              Concentrate                                      t = process process pH                                                      ______________________________________                                         1 min   85          91.3      13.03                                             9 min -- 75.4 13.03                                                          15 min -- 71.4 13.03                                                          24 h -- 44.4 12.88                                                          ______________________________________                                    

EXAMPLE 17

An active biocidal ingredient derived from ammonium hydroxide mixed withSDS, and NaOCl was prepared as follows: Amine source: NH₄ OH (2.4%) inSDS (sodium dodecyl sulfate, 0.8%. pH: 10.71). NaOCl: 11.5% expressed asCl₂. Continuous process: dilution factor 1:13.3; molar ratio N/Cl₂ :1.5:1.0 Concentrated active biocidal ingredient: 0.86% expressed as Cl₂.Batch production: dilution factor 1:20; molar ratio N/Cl₂ : 2:1.

The following table sets forth the yield (%) of the active biocidalingredient.

                  TABLE 17                                                        ______________________________________                                                 Batch       Continuous                                                                              Concentrate                                      t = process process pH                                                      ______________________________________                                         2 min   72.4        111.3     13.00                                            18 h 0  51.16 13.00                                                         ______________________________________                                    

EXAMPLE 8

An active biocidal ingredient derived from ammonium bromide and Acumer2000 (a polyacrylate based dispersant, product of Rohm and Haas) wasprepared as follows: Amine source: NH₄ Br (14%) mixed with Acumer 2000(20%). (Initial pH of the amine source was 4.15; NaOH was addedgradually to the amine source.) Measurements of the residual activebiocidal ingredient were conducted 2 minutes after production and showedthe following yields (%); depending on pH of the concentrated activeingredient:

                  TABLE 18                                                        ______________________________________                                                       pH of                                                          Batch     Continuous concentrated active                                                                        t (min) to                                    process process ingredient decomposition                                    ______________________________________                                        0         4.42       5.12         <1 m                                          0 100 7.47  3 m                                                               0 100 7.75   6 min                                                            0 100 9.13  15 min                                                          ______________________________________                                    

While the invention has been described with respect to many preferredembodiments, it will be appreciated that these are set forth forpurposes of example, and that many other variations, modifications andapplications of the invention may be made.

I claim:
 1. A method of treating a liquid to inhibit growth of livingorganisms therein by adding to the liquid an active biocidal ingredientformed by mixing an oxidant comprising hypochlorite and an amine sourcecomprising ammonium bromide, comprising:producing a predetermineddilution of said oxidant; producing a predetermined dilution of saidamine source; synchronously metering said two dilutions into a conduitto continuously mix therein according to a predetermined ratio toproduce said active biocidal ingredient having an effective amount ofreproducibility, stability and efficacy in situ in said conduit; andcontinuously injecting said active biocidal ingredient, as it isproduced in situ in said conduit, directly from said conduit into theliquid being treated.
 2. The method according to claim 1, wherein saidpredetermined dilution of the oxidant is continuously producedimmediately before it is synchronously metered into the conduit withsaid predetermined dilution of the amine source.
 3. The method accordingto claim 2, wherein said predetermined dilution of the amine source iscontinuously produced immediately before it is synchronously meteredinto the conduit with said predetermined dilution of the oxidant.
 4. Themethod according to claim 1, wherein said active biocidal ingredient, asproduced in situ in said conduit, has a pH of at least 7.0 before beingintroduced into the liquid to be treated.
 5. The method according toclaim 4, wherein said active biocidal ingredient, as produced in situ insaid conduit, has a pH of over 10.0 before being introduced into theliquid being treated.
 6. The method according to either of claims 4 or5, wherein the liquid being treated has a pH of 5-10.5 before saidactive biocidal ingredient is injected into it.
 7. The method accordingto claim 6, wherein the liquid being treated has a pH of 7-9 before saidactive biocidal ingredient is injected into it.
 8. The method accordingto claim 1, wherein said active biocidal ingredient, as produced in situin said conduit, is injected into the liquid being treated to aconcentration of 0.5-300 ppm expressed as chlorine.
 9. The methodaccording to claim 8, wherein said active biocidal ingredient, asproduced in situ in said conduit, is injected into the liquid beingtreated to a concentration of 3-10 ppm expressed as chlorine.
 10. Themethod according to claim 1, wherein said amine source contains adetergent, surfactant, water treatment chemical, or a base.
 11. Themethod according to claim 1, wherein said amine source has aconcentration of 0.1 to 50%.
 12. The method according to claim 1,wherein said amine source has a concentration of 2.5 to 30% and isequimolar to Cl₂.
 13. The method according to claim 1 wherein saiddiluted amine source has a concentration of 0.1 to 6.0% and is equimolarto diluted oxidant solutions.
 14. The method according to claim 1,wherein said oxidant is selected from the group of sodium hypochloriteand calcium hypochlorite.
 15. The method according to claim 1, whereinsaid oxidant is a solution of hypochlorite, and said amine source is asolution containing an excess of base corresponding to at least 10%NaOH.
 16. The method according to claim 1, wherein a base issynchronously added to said amine source to stabilize the activebiocidal ingredient.
 17. The method according to claim 1, wherein saidoxidant has a concentration of 0.1-15% expressed as Cl₂.
 18. The methodaccording to claim 17, wherein said oxidant has a concentration of 5-15%expressed as Cl₂.
 19. The method according to claim 17, wherein saidoxidant dilution has a concentration of 0.1 to 2.0% expressed as Cl₂.20. A method of treating a liquid to inhibit growth of living organismstherein by adding to the liquid an active biocidal ingredient formed bymixing an oxidant comprising hypochlorite and an amine source comprisingammonium bromide, characterized in:continuously and synchronouslyinjecting a quantity of said oxidant into a first stream of waterpassing through a first conduit to produce therein a predetermineddilution of said oxidant; continuously and synchronously injecting aquantity of said amine source into a second stream of water passingthrough a second conduit to produce therein a predetermined dilution ofsaid amine source; continuously and synchronously injecting said firstand second streams into a third conduit according to a predeterminedratio to produce said active biocidal ingredient in situ in said thirdconduit; and continuously injecting said active biocidal ingredient, asit is produced in situ in said third conduit, from said third conduitinto the liquid being treated.
 21. The method according to claim 20,wherein said oxidant is continuously injected into said-first stream ofwater by a first dosing pump connected to a reservoir of said oxidant.22. The method according to claim 21, wherein said amine source iscontinuously injected into said second stream of water by a seconddosing pump connected to a reservoir of said amine source andsynchronously operated with said first dosing pump.
 23. Apparatus fortreating a liquid to inhibit growth of living organisms therein byadding to the liquid an active biocidal ingredient formed bycontinuously and synchronously mixing an oxidant comprising hypochloriteand an amine source comprising amonium bromide, comprising:(a) a firstdiluter producing a predetermined dilution of said oxidant; (b) a seconddiluter producing a predetermined dilution of said amine source; (c) amixer continuously and synchronously mixing said two dilutions in aconduit according to a predetermined ratio to produce said activebiocidal ingredient in situ in said conduit; and (d) an injectorcontinuously injecting said active biocidal ingredient, as it isproduced in situ in said conduit, directly from said conduit into theliquid being treated.
 24. Apparatus according to claim 23, wherein:saidfirst diluter comprises a first conduit including a first dosing pump,connected to a reservoir of the oxidant for continuously pumping theoxidant into a first stream of water in proportion to the rate of flowof water through said first conduit; said second diluter comprises asecond conduit including a second dosing pump, connected to a reservoirof the amine source for continuously and synchronously pumping into asecond stream of water a quantity of the amine source corresponding tothe rate of flow of water through said second conduit; and said mixercomprises a third conduit connected to said first and second conduits tomix said two dilutions therein, to produce said active biocidalingredient in situ in said third conduit as the active biocidalingredient is continuously injected into the liquid being treated. 25.The apparatus according to claim 24, wherein said dosing pumps areventuri tubes conducting their respective streams of water.
 26. Theapparatus according to claim 25, wherein each of said first and secondconduits includes a water control valve for controlling the flow rate ofthe water therethrough to their respective venturi tubes.
 27. Theapparatus according to claim 25, wherein the connection of each of saidreservoirs to its respective venturi tube includes a dosage controlvalve for controlling the flow rate therethrough of the oxidant andamine source from their respective reservoirs to the respective venturitubes.
 28. The apparatus according to claim 24, wherein said dosingpumps are peristaltic pumps.
 29. The apparatus according to claim 24,wherein said dosing pumps are pulsatile pumps.
 30. The apparatusaccording to claim 24, including means for continuously filling each ofsaid reservoirs in order to maintain a constant level therein.
 31. Theapparatus according to claim 24, wherein said third conduit includes anoptical sensor for sensing the optical properties of the active biocidalingredient formed in situ therein and flowing therethrough to the waterbeing treated, and for controlling said dosage pumps in response to saidsensed optical properties.
 32. The apparatus according to claim 24,wherein said third conduit includes a pH sensor for sensing the pH ofthe active biocidal ingredient formed in situ therein and flowingtherethrough to the water being treated, and for controlling said dosagepumps in response to the sensed pH.